CAusality and the delayed choice quantum eraser

Admittedly, I do not understand this. Is the experiment referenced above claiming that it can predict the future, so to speak, of the photons by observing then erasing the measurement information of the pattern of a photon, or are they saying they can cause the photon to act in a way they couldn’t before (i.e. the double slit) ?

Is this about reading information before it happens or causality (or neither or both?)

Causality and the delayed choice quantum eraser.

They have got to stop doing LSD, it’s affecting their science.


As I understand it, there are three classes of explanations for the delayed choice quantum eraser:

  1. Super-determinism. The photon “predicts” the future as to what the experimenter will decide to do, and acts accordingly right from the beginning of the experiment.

  2. Non-locality. The choice the experimenter makes along the one path is instantaneously transmitted to the other path.

  3. Many worlds. Both possibilities happen along each path, and the corresponding worlds are brought together in the correct manner at the end of the experiment.

In my opinion, none of these explanations are particularly satisfactory.

There are several quantum phenomena which are mysterious in their interpretation (the interpretation belongs to metaphysics, not science, cause the interpretations are all consistent with the experimental results). As Richard Feynmann said, “anyone who says he understands quantum mechanics, doesn’t”.(that’s a paraphrase, since I can’t find the original quotation.) Here are some websites that do a good job (in not too technical language) of explaining the quantum eraser and/or delayed choice experiments.
note: there is a link at the bottom of this wikipedia article to “retrocausality”, which is part of your question.
this is a good, non-technical (no diagrams) explanation.
I have (in another post) talked about Raymond Chiao’s interpretation of quantum eraser/delayed choice experiments: a Neo-Berkeleyan view that the observer is required to detect reality, and that the ultimate observer is God, who observes the universe. see
the thread “God, the observer, continually creates the universe.”
Hope this is helpful.

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit